This invention relates to inherently tacky, elastomeric, solvent-dispersible, solvent-insoluble, polymeric microspheres and a process for preparing same.
In U.S. Pat. No. 3,691,140 to Silver, there are disclosed inherently tacky acrylate copolymer microspheres comprising a major portion of at least one alkyl acrylate ester and a minor portion of an ionic monomer.
As discussed in the Silver patent, the microspheres can be unexpectedly prepared by suspension polymerization techniques, which historically have been considered unsuitable for preparation of tacky polymers. In the technique described by Silver, the microspheres are prepared utilizing an emulsifier in an amount greater than the critical micelle concentration in the absence of externally added protective colloids or the like. The Silver microspheres are copolymeric in nature and require an ionic comonomer as an essential component thereof.
It has now been found that inherently tacky microspheres having physical properties similar to those of the Silver patent, i.e., inherent tack, infusibility, solvent dispersibility, and solvent insolubility, can be prepared which are not limited to copolymers, but may also be homopolymers, and do not contain an ionic comonomer. The microspheres are prepared by aqueous suspension polymerization, but have as an essential ingredient in their preparation a hereinafter defined suspension stabilizer.